A vehicle airbag is an inflatable restraint device that is deployed during a car crash to protect a vehicle occupant from sustaining injury. In order to prevent the vehicle occupant from colliding with the instrument panel or steering wheel during a frontal crash or the intruding door during a side collision, the airbag needs to be inflated within a fraction of a second. To meet the stringent time demands placed upon the airbag, a gas supply source needs to be able to quickly release inflation gas into the vehicle airbag. One type of gas supply source that is known in the art is a cold gas inflator that stores a quantity of stored pressurized gas. This type of inflator operates by releasing the inert gas to inflate the airbag. Another common type of inflator known in the art is the hybrid inflator, which includes a heating component and an inert gas component. This type of inflator operates by releasing a mixture of hot gas and inert gas.
A representative hybrid inflator is taught in U.S. Pat. No. 6,010,153, which is incorporated herein in its entirety. The hybrid inflator has a pressure vessel for storing a pressurized gas and a pyrotechnic heater assembly having a pyrotechnic heating material. Upon receiving an activating signal, an igniter ignites the pyrotechnic heating material, which in turn causes the pressure vessel to open. The hot gaseous products from the pyrotechnic heating material and the inert gas exit the inflator.
For cold gas inflators, the inert gas is retained in the pressure vessel by a sealing element. The sealing element blocks the discharge opening of the pressure vessel so that inert gas cannot exit the inflator. In order for the cold gas inflator to release inert gas, the sealing element must be ruptured or destroyed. U.S. Pat. No. 6,247,725 B1 teaches a cold gas inflator having a sealing element for blocking the inert gas from exiting the pressure vessel. A supporting member that is sandwiched between the sealing element and a counterbearing supports the sealing element. The cold gas inflator has a triggering device that when activated removes the support member for the sealing element. Without the support member, the sealing element will burst because it cannot withstand the pressure from the inert gas. US 2002/0074036 A1 also teaches a cold gas inflator that has a support member, and this published patent application is incorporated herein in its entirety by reference. The sealing element is located in the gas discharge opening with a support member adjacent thereto. A locking element is disposed in a locking position between a side of the support member and a first abutment. A second abutment also supports the support member. A gas releasing device moves the locking element, which causes the sealing element and support member to burst thereby providing an unobstructed discharge opening for the escape of the inert gas.
While various approaches for opening a pressure vessel having a support member are taught in the prior art, there is a need to develop cheaper opening devices for both cold gas inflators as well as hybrid inflators.